Less Is More: Negative Relationship Between Biomass Density And Sea Lice Infestation In Marine Salmon Farming

The relationship between biomass density and sea lice infestation is of particular interest in marine salmonid aquaculture. Data from a commercial fish farmer with parallel production of both organic and conventional salmon at the same site made it possible to study aspects of this relationship in a field situation. The maximum allowed biomass density for organically produced salmon is 10 kg/m3 and 25 kg/m3 for conventionally produced salmon. The focus of this study was to compare sea lice infestation on salmon in the two productions types and related biomass densities synchronously. Organic salmon had significantly higher levels of sea lice compared to salmon in conventional production. Mortality rate and growth rate were not significantly different between the production strategies.